Alkylation of paraffin hydrocarbons



Jan. 12, 1943. c. B. LINN 2,307,

ALKYLATION OF PARAFFIN HYDROCARBONS Filed July 5, 1940 FRACTION/1T0 INVENT OR.

,g'v/M/z/ ay T Patented a... I2, 1943 stares pairs orr c a ALKYLATION' F PARAFFIN HYDROCARBONS tion of Delaware Application July 5, 1940, Serial No. 344,104

16 Claims.

This invention is concerned with the interaction of branched chain paraflinic hydrocarbons with alkyl fluorides in the presence of a catalyst. It is more specifically concerned with a simple and easily regulated process involvin the use of a liquid catalyst which is altered only slightly in the course of the reaction but which catalyzes the desired reactions with a maximum of efficiency.

Processes for the formation of higher molecular weight branched chain paraffins from lower boiling less highly branched chain paraflins are of importance from the standpoint of the motor fuel industry which demands increasing quantities of substantially saturated hydrocarbons boiling within the range of gasoline and particularly saturated motor fuels of high antiknock value.

In one specific embodiment the present invention comprises a process for alkylating branched chain paraifimc hydrocarbons by alkyl fluorides in the presence of liquid hydrogen fluoride to form higher boiling branched chain parafiinic hydrocarbons of motor fuel boiling range and high antiknock value.

Considerable quantities of branched chain butane, pentanes, and higher boiling paraflins are available in the gaseous and lower boiling products resulting from the distillation and/ or cracking of petroleum oils and of other hydrocarbonaceous oils. Proper segregation by fractionation and other methods makes available substantial amounts of isoparafiinic hydrocarbons which may be alkylated by alkyl fluorides in the presence of catalysts to give higher boiling and more highly branched parafiinic hydrocarbon of improved antiknock value. In accordance with the present invention interaction of isoparaiflnic hydrocarbons with alkyl fluorides is brought about in the presence of substantially anhydrous hydrogen fluoride. This reaction forms substantially saturated hydrocarbons of higher boiling range and simultaneously produces hydrogen fluoride which may be utilized further as catalyst for alkylating a further quantity of the isoparaflinic hydrocarbon charged.

Alkyl fluorides used as alkylatin agents in the process of this invention may be formed by the addition of hydrogen fluoride to mono-olefinic hydrocarbons at a temperature within the approximate range of 60 to +100 C., and more preferably at a temperature of the order of 30 to 0 0., and under a pressure suflicient to maintain in liquid phase a substantial proportion of the reaction mixture. At the higher temperatures polymerization tends to occur which interferes with the direct conversion of the original olefin into alkyl fluorides. Such a formation of alkyl it can be used in apparatus which is cooled to I maintain temperatures below this point or it can be used at higher temperatures if sufficient pressure is maintained upon the apparatus. By maintaining an excess of isoparafiin at all times, generally up to approximately 20 times the molecular proportion of alkyl fluoride present, formation of olefin polymers is avoided with the result that there is a relatively high conversion of alkyl fluorides into alkylated parafiinic hydrocarbons. Also formation of hydrogen fluoride occurs during the alkylation reaction. The resulting, hydrogen fluoride may be employed as alkylating catalyst or it may be utilized in the production of a further quantity of alkyl fluoride to be returned to the process.

In operating the present process a preferred procedure is to agitate a mixture of liquid hydrogen fluoride and an isoparaflin and gradually introduce thereto a, mixture of an alkyl fluoride and an isoparaffln suitably below the surface of the hydrogen fluoride-isoparaflin mixture. In the batch operation-of this process, the agitation may be stopped and'the upper hydrocarbon layer removed and fractionated to recover unchanged paraflms and the desired alkylated products. Obviously the process may be made continuous by' providing a mixing zone; as a reactor containing baiiles and/or orifices, in which suflicient time may be given generally in the approximate range of 1-10 minutes for the completion of the desired alkylation reaction followed by a settling zone from which a hydrocarbon layer may be withdrawn and fractionated to recover desired alkylat ed products and unconverted isoparafiins for recycling, while the lower hydrogen fluoride layer may be pumped back to the alkylation step for further separation. The aforementioned reaction of an isoparaffin with an alkyl fluoride may be carried out at a temperature in the ap proximate range of l0 to C. but preferably at a temperature of approximately 20 C. Pressure has been found to have little efiect on the reaction but it should preferably be suflicient to compensate for the vapor pressure of the reactants. Reaction maybe attained to advantage by contacting the isoparaflinic hydrocarbon, al-

kyl fluoride, and hydrogen fluoride in the liquid hydrocarbon fraction m ay be introduced through line I containing vaiveiit o-line 3;-contairiing valve 4 to pump 5 while hydrogen fluoride is introduced to line 3 by way of line 6 containing valve 1. Pump 5 discharges through line 8 and valve 9. The mixture of isoparaflin and hydrogen fluoride being conducted through line 8 is therein commingled with a regulated and continuous stream of an alkyl fluoride or of an alkyl fluoride-isoparafiin mixture introduced through line In and valve H to pump l2 which discharges through line l3 and valve H to line 8, already mentioned, from which the commingled mixture passes to coil l5 contained in cooler N5 of any suitable construction and capacity for maintaining the temperature of reaction below any desired level while simultaneously permitting sufilcient time of contact for completion of the desired reactions.

From coil i5 the reaction products follow line ll' containing valve |8 to separator IS in which is efiected a separation of hydrogen fluoride and hydrocarbons. The hydrogen fluoride layer is withdrawn from separator I9 through line containing valve 2| to pump 22 which discharges through line 23 and valve into line 3 leading to the suction side of pump 5 so that the hydrogen fluoride catalyst may be recycled. If desired, a portion of the hydrogen fluoride being discharged by pump 22 through line 23 may be con ducted therefrom through line 26 and valve 21 to storage or to other use such as the preparation of additional alkyl fluorides by reaction of hydrogen fluoride with a mono-olefin.

The hydrocarbon layer in the upper portion of separator I9 may be passed through line 28 and valve 29 to fractionator 30 containing reboiler coil 3| and.provided with vapor line 32 and valve 33 through which lower boiling hydrocarbons may be released as an overhead fraction while higher boiling alkylated products may be withdrawn from the bottom of iractionator 30 through line 34 containing valve 35 to further cooling, not shown, and to storage.

The unconverted lower boiling hydrocarbons passing through line 32 may beconducted through condenser 36 and run-down line 31 containing valve 38 to receiver 39 equipped with conventional gas release line 40 containing valve 4| and with a liquid draw-off line 42 containing valve 43 leading to pump 44 which discharges through line 45 containing valve 46 to storage if desired, but ordinarily through line 25 containing valve 41 and leading to the suction side of pump 5, already mentioned, to permit recycling of unconverted isoparafflns to further allgvlation.

The exact temperature and pressure to be employed when alkylating various isoparaflins with various alkyl fluorides will depend upon the activity and physical characteristics of the reactants involved so that best results will be obtained when conditions are first determined on small scale apparatus. As a ruleexcessively elevated temperatures are neither necessary nor desirable and only sufficient pressure should be used to prevent excessive evaporation of the catalyst or of the isoparaflin and alkyl fluoride.

The following spec'iflc examples are introduced as representative of results obtainable by the process described, although with no intention oi unduly limiting the generally broad scope of the invention;

EXAMPLE I A pressure autoclave equipped with a mechanical stirrer was charged with parts by weight of anhydrous hydrogen fluoride and 200 parts by weight (3.5 molecular proportions) of isobutane. The autoclave was maintained at 20 C. while 124 parts by weight (2.0 molecular proportions) of isopropyl fluoride was introduced thereto over a period of 1 hour during which time the reaction was accompanied by an evolution of heat.

The reaction mixture recovered was separated into 135 parts by weight of hydrogen fluoride, 102 parts by weight of isobutane, and 170 parts by weight of a colorless and substantially saturated liquid hydrocarbon mixture which was found to contain substantially no fluorine. Fractional distillation of the liquid hydrocarbon mixture obtained showed it to have the composition given in Table I:

TABLE I Distillation of liquid product formed from isobutane and isoprdpyl fluoride in the presence of hydrogen fluoride EXAMPLE II A mixture of 112 parts by weight of isopentane, parts by weight of hydrogen fluoride, and 79 parts by weight of isopropyl fluoride was agitated for 2.5 hours at 35 C. in a pressure autoclave similar to that indicated in Example I.

The reaction mixture recoveredcontained 9 parts by weight of propane, 10 parts by weight of isobutane, 18 parts by weight of unconverted isopentane, and 113 parts by weight of a higher boiling substantially saturated hydrocarbon mixture. A distillation of the substantially saturated hydrocarbon mixture showed it to have the composition indicated in Table II.

TABLE II Distillation of liquid product formed from zsopentane and isomopzll fluoride in the presence of hydrogen fluoride "Boiling range of fraction, "C. Volume per cent 50-75 12 75-95 10 95-125 23 -150 13 -175 12 -225 21 Above 225 9 These results indicate that approximately equal molecular proportions of isopentane and isopropyl fluoride reacted to produce the substantially saturated hydrocarbon mixture of a composition indicated in Table II.

The character of the process of the present in- .a branched chain paraflin which comprises subjecting a molal excess of said branched chain paraflln to contact withan alkyl fluoride in the presence of hydrogen fluoride.

3. A process for producing alkyl derivatives of a branched chain paraifln which comprises subjecting a molal excess of said branched chain paraffin to treatment with an alkyl fluoride in the presence of hydrogen fluoride at a temperature between about l and about +75 C. under sufflcient pressure to maintain substantially liquid phase conditions.

4. A process for producing isomeric octanes which comprises subjecting isobutane to treatment with a butyl fluoride in the presence of hydrogen fluoride.

5. A process for producing isomeric octanes .which comprises subjecting a molal excess of isobutane to treatment with a butyl fluoride in the presence of hydrogen fluoride.

6. A process for producing isomeric octanes which comprises subjecting a molal excess of isobutane to treatment with a butyl fluoride in the presence of hydrogen fluoride at a temperature between about l0 and about +75 C. and under suificient pressure to maintain substantially liquid phase conditions.

7. A process for alkylating a liquid isoparaflin hydrocarbon which comprises intimately mixing said hydrocarbon with liquid hydrogen fluoride; introducing an alkyl fluoride to the mixture; cooling to maintain the reaction mixture at a temperature between about and about. +75 C., separating products of the reaction into unconverted isoparafi'ln and alkyl fluoride, alkylated products, and hydrogen fluoride; and returning unconverted isoparaflin, alkyl fluoride, and hydrogen fluoride to further reaction.

8. A process forproducing alkylderivatives of an isoparafiin which comprises subjecting an isoparaffln in admixture with normal paraflins to treatment with an alkyl fluoride in the presence of hydrogen fluoride.

9. A process for producing alkyl derivatives of an isoparaflin which comprises subjecting a molal excess of an isoparaifin in admixture with normal paraffins to treatment with analkyl fluoride in the presence of hydrogen fluoride.

10. A process for producing alkyl derivativesof branched chain paraflins which comprises subjecting a molal excess of branched chain paraffins in admixture with normal paraflins to treat ment with an alkyl fluoride in the presence of hydrogen fluoride at a temperature between about 10 and about +75 C. under suflicient pressure to maintain substantially liquid phase conditions.

11. A'process for producing a substantially saturated alkylation product which comprises subjecting a mixture of isobutane and normal butane to treatment with an alkyl fluoride in the presence of hydrogen fluorideat a temperature perature between about --10 and a" between about -10 and about +75 C. under sufflcient pressure to maintain substantially liquid phase conditions. 4

. 12. A process for producing a substantially saturated alkylation product which jecting a mixture or isopentane and an alkylflu oride to contact with hydrogen flu under suflicient pressure to maintain substantially liquid phase conditions.

13. A process for producing isomeric heptanes which comprises subjecting a molal excess of isobutane to treatment with presence of hydrogen fluoride at a temperature between about -10 and about 75 C. and under sufficient pressure to maintain substantially liquid phase conditions. I

14. A process'for producing isomeric octanes which comprises subjecting a molal excess of isopentane to treatment with a propyl fluoride in the presence of hydrogen fluoride at a temperature between about -10 and about +75 C. and under suflicient pressure to maintain substantially liquid phase conditions.

15. A process for synthesizing hydrocarbons which comprises reacting a branched chain paraffln with an alkyl fluoride in the presence of substantially anhydrous hydrogen fluoride.

16. A process for synthesizing hydrocarbons which comprises reacting a branched chain paraflin with an alkyl fluoride in the presence of of hydrogen fluoride.

comprises sub:

a propyl fluoride in the Y CA/RL B. LINN. I I 

